Mr. Guo, who told the authorities he comes from the far west region of Xinjiang, set off from coastal Fujian Province on a flotation device made from bamboo and Styrofoam. Mr. Pu said officials had been tracking his progress by radar.

After his arrest, he told Taiwanese reporters that he was inspired to make the perilous journey by Taiwan’s presidential race, which pits the incumbent Ma Ying-jeou against two opponents. “I want to see your elections, with campaign flags flying all over the place,” he said.

The elections, which take place Jan. 14, have piqued considerable interest in China, which is led by a Communist government keen to dampen the democratic yearnings of its people. After decades of authoritarian rule, Taiwan — considered by Beijing to be a breakaway province — held its first direct presidential elections in 1996.